engine seized up help kz750

I feel for ya bro. You need to pull the head. If engine now turns over you will see marks where piston met valve. If engine will still nor turn over then you will have bottom end or cylinder problem. Don't sell the bike, calm down and check it out. May not be too bad. We are here for you...

ok i will pull it. I mixed my old cams with my new head cause the old ones where cleaner. do cams ever seize? One of the wrist pins was a bit of a bear to get in place but once i did the engine seemed to turn ok.......

Just a thought, you mention using +1 pistons and barely used cylinders, and that you honed it. Was the piston to cylinder clearance by the book? You don't mention boring and I would think using +1 pistons you need to...

the jugs were bored out plus 1 and i had them honed. I never checked it with a micrometer but my mechanic eyeballed them and said I had a good fit.......

jammor wrote:

And I failed to mention the original reason I rebuilt the top end was because the engine seized. Perhaps I simply have a bad oil pump- I think I really failed to consider what lower engine components could be bad...??

Sounds like the original problem is still there. was your engine oil light coming on before it siezed the first time?

It may be unrelated to this seizure, but next time you rebuild don't let your "mechanic" "eyeball" anything. Things like ring endgap, piston/cylinder clearance, etc. are measured in thousandths of a mm. Nobody's eyeballs are that accurate. Ed

Thanks 650ed and especially bountyhunter for all of your responses. I was really trying to avoid tearing the engine down and all of your advice made me realize how to do it step by step. The results are in and here they are:

nutshell: nothing I replaced failed!!! yeeehhaawww problem is in the crank that seized which was my initial problem to begin with but i missed it (and that sucks a big one).

I took the cams off- no scoring, burned marks, black marks, metal, etc---and lots of oil up there

still couldn't budge the engine with the cams off

pulled the head

no valve damage. the cylinders are on the bottom

pulled the cyls easy. They were not stuck and look just like when i got them back from the shop that honed them. No blown head gasket. No oil leaking outside the engine. No oil light ever went on (and it works cause i tested it).

Still cant budge the engine with the cyls off.

I think my problem was a bad journal on the crank. I had hoped refreshing the top end would fix my problem (initial engine seizure prior to the top end rebuild) and hoped the bottom end was good. Now I know it wasn't.

I do now appreciate using a micrometer as 650ed recommends for my peace of mind and perhaps the next time I put this together I will buy new parts---BUT i have a great top end here that didn't fail(thanks smith) and so I may use it again!!! If I do i will probably just pull it apart before I post too many questions:)

This has been a great learning experience for me and I appreciate all of your help.

So now I have a lead on an old kz 750 engine dirt cheap. If the crank turns I will buy it and put my top end on (with new rubber seals) and new other gaskets of course and see if it works. It is amazing how quicly I can tear this thing down now--- took 20 hours to assemble first time and 2 hours to take apart!!!

My mechanic says just try the old engine before I disassemble it and try to buy new crank bearings, etc. because they are expensive. he says i have probably damaged my current engine beyond repair. Says i can get the crank welded and resized but it never lasts---does that sound right to y'all

thanks
jim

the engine now

sorry cant get the pic to load

jammor wrote:

My mechanic says just try the old engine before I disassemble it and try to buy new crank bearings, etc. because they are expensive. he says i have probably damaged my current engine beyond repair. Says i can get the crank welded and resized but it never lasts---does that sound right to y'all

thanks
jim

Pretty much. Fixing the seized one would cost a lot. It's possible that a used one would have a usable bottom end: my 750 twin has about 80k miles and the bottom is still good (as far as I know). The bottoms on KZ's are supposed to be really strong.

I don't know if new bearings are available for the twins, Kawi doesn't stock many parts for them unless they are used in other models.

Bountuhunter said "I don't know if new bearings are available for the twins, Kawi doesn't stock many parts for them unless they are used in other models".

If its 13034-044 you're referring to, they're $15 each.

my two cents,, after reading the whole post, I think I would look for another mechanic, seems that all the eye ball fitting and feeling he did, he didnt take the time to check the whole engine and find the real reason it went bad to start with.